drm/apple: Get rid of the piodma dummy driver

It's only needed to configure the display contoller's iommu to share
buffers between the DCP co-processor and the display controller.
Possible concern is runtime PM for it and its iommu. If we don't set it
up the power domain might never go to lower power states even if it
could.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/Makefile

@@ -9,11 +9,9 @@ apple_dcp-y += iomfb_v12_3.o
 apple_dcp-y += iomfb_v13_3.o
 apple_dcp-$(CONFIG_TRACING) += trace.o
 
-apple_piodma-y := dummy-piodma.o
 
 obj-$(CONFIG_DRM_APPLE) += appledrm.o
 obj-$(CONFIG_DRM_APPLE) += apple_dcp.o
-obj-$(CONFIG_DRM_APPLE) += apple_piodma.o
 
 # header test
 

drivers/gpu/drm/apple/apple_drv.c

@@ -556,26 +556,6 @@ const struct component_master_ops apple_drm_ops = {
 	.unbind	= apple_drm_unbind,
 };
 
-static const struct of_device_id apple_component_id_tbl[] = {
-	{ .compatible = "apple,dcp-piodma" },
-	{},
-};
-
-static int add_display_components(struct device *dev,
-				  struct component_match **matchptr)
-{
-	struct device_node *np;
-
-	for_each_matching_node(np, apple_component_id_tbl) {
-		if (of_device_is_available(np))
-			drm_of_component_match_add(dev, matchptr,
-						   component_compare_of, np);
-		of_node_put(np);
-	}
-
-	return 0;
-}
-
 static int add_dcp_components(struct device *dev,
 			      struct component_match **matchptr)
 {
@@ -600,9 +580,6 @@ static int apple_platform_probe(struct platform_device *pdev)
 	struct component_match *match = NULL;
 	int num_dcp;
 
-	/* add PIODMA mapper components */
-	add_display_components(mdev, &match);
-
 	/* add DCP components, handle less than 1 as probe error */
 	num_dcp = add_dcp_components(mdev, &match);
 	if (num_dcp < 1)

drivers/gpu/drm/apple/dcp.c

@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/of_device.h>
+#include <linux/of_platform.h>
 #include <linux/slab.h>
 #include <linux/soc/apple/rtkit.h>
 #include <linux/string.h>
@@ -317,17 +318,39 @@ static void dcp_work_register_backlight(struct work_struct *work)
 	mutex_unlock(&dcp->bl_register_mutex);
 }
 
-static struct platform_device *dcp_get_dev(struct device *dev, const char *name)
+static int dcp_create_piodma_iommu_dev(struct apple_dcp *dcp)
 {
-	struct platform_device *pdev;
-	struct device_node *node = of_parse_phandle(dev->of_node, name, 0);
+	int ret;
+	struct device_node *node = of_get_child_by_name(dcp->dev->of_node, "piodma");
 
 	if (!node)
-		return NULL;
+		return dev_err_probe(dcp->dev, -ENODEV,
+				     "Failed to get piodma child DT node\n");
+
+	dcp->piodma = of_platform_device_create(node, NULL, dcp->dev);
+	if (!dcp->piodma) {
+		of_node_put(node);
+		return dev_err_probe(dcp->dev, -ENODEV, "Failed to gcreate piodma pdev for %pOF\n", node);
+	}
+
+	ret = dma_set_mask_and_coherent(&dcp->piodma->dev, DMA_BIT_MASK(42));
+	if (ret)
+		goto err_destroy_pdev;
+
+	ret = of_dma_configure(&dcp->piodma->dev, node, true);
+	if (ret) {
+		ret = dev_err_probe(dcp->dev, ret,
+			"Failed to configure IOMMU child DMA\n");
+		goto err_destroy_pdev;
+	}
+	of_node_put(node);
 
-	pdev = of_find_device_by_node(node);
+	return 0;
+
+err_destroy_pdev:
 	of_node_put(node);
-	return pdev;
+	of_platform_device_destroy(&dcp->piodma->dev, NULL);
+	return ret;
 }
 
 static int dcp_get_disp_regs(struct apple_dcp *dcp)
@@ -433,8 +456,6 @@ static int dcp_comp_bind(struct device *dev, struct device *main, void *data)
 	if (IS_ERR(dcp->coproc_reg))
 		return PTR_ERR(dcp->coproc_reg);
 
-	of_platform_default_populate(dev->of_node, NULL, dev);
-
 	if (!show_notch)
 		ret = of_property_read_u32(dev->of_node, "apple,notch-height",
 					   &dcp->notch_height);
@@ -480,16 +501,10 @@ static int dcp_comp_bind(struct device *dev, struct device *main, void *data)
 	else
 		dcp->connector_type = DRM_MODE_CONNECTOR_Unknown;
 
-	/*
-	 * Components do not ensure the bind order of sub components but
-	 * the piodma device is only used for its iommu. The iommu is fully
-	 * initialized by the time dcp_piodma_probe() calls component_add().
-	 */
-	dcp->piodma = dcp_get_dev(dev, "apple,piodma-mapper");
-	if (!dcp->piodma) {
-		dev_err(dev, "failed to find piodma\n");
-		return -ENODEV;
-	}
+	ret = dcp_create_piodma_iommu_dev(dcp);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				"Failed to created PIODMA iommu child device");
 
 	ret = dcp_get_disp_regs(dcp);
 	if (ret) {
@@ -546,8 +561,10 @@ static void dcp_comp_unbind(struct device *dev, struct device *main, void *data)
 	if (dcp && dcp->shmem)
 		iomfb_shutdown(dcp);
 
-	platform_device_put(dcp->piodma);
-	dcp->piodma = NULL;
+	if (dcp->piodma) {
+		of_platform_device_destroy(&dcp->piodma->dev, NULL);
+		dcp->piodma = NULL;
+	}
 
 	devm_clk_put(dev, dcp->clk);
 	dcp->clk = NULL;
@@ -563,6 +580,7 @@ static int dcp_platform_probe(struct platform_device *pdev)
 	enum dcp_firmware_version fw_compat;
 	struct device *dev = &pdev->dev;
 	struct apple_dcp *dcp;
+	int ret;
 
 	fw_compat = dcp_check_firmware_version(dev);
 	if (fw_compat == DCP_FIRMWARE_UNKNOWN)
@@ -577,6 +595,12 @@ static int dcp_platform_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, dcp);
 
+	ret = devm_of_platform_populate(dev);
+	if (ret) {
+		dev_err(dev, "failed to populate child devices: %d\n", ret);
+		return ret;
+	}
+
 	return component_add(&pdev->dev, &dcp_comp_ops);
 }